Washington — A federal judge on Wednesday blocked President Trump’s plan to sharply restrict access to the nation’s asylum system, a blow to the president’s sweeping crackdown on immigration into the United States.

U.S. District Judge Randolph Moss ruled in favor of 13 individuals seeking asylum in the U.S. and three immigrants’ rights groups who argued that a proclamation signed by Mr. Trump on his first day back in office — which has been a pillar of his immigration agenda — is unlawful. 

In his decision, Moss ruled that neither the Immigration and Nationality Act nor the Constitution give the president and administration officials “the sweeping authority” asserted in his proclamation and subsequent guidance implementing the directive.

“The court recognizes that the executive branch faces enormous challenges in preventing and deterring unlawful entry into the United States and in adjudicating the overwhelming backlog of asylum claims of those who have entered the country,” he wrote. “But the INA, by its terms, provides the sole and exclusive means for removing people already present in the country.”

Moss said that a pair of provisions of federal immigration law do not provide “the president with the unilateral authority to limit the rights of aliens present in the United States to apply for asylum.”

He further found that the Constitution does not give the president the authority to “adopt an alternative immigration system, which supplants the statutes that Congress has enacted and the regulations that the responsible agencies have promulgated.”

In addition to finding Mr. Trump’s plan to limit access to asylum, the judge granted the plaintiffs’ request to certify a class of all people covered by the president’s proclamation or its implementation who are or will be in the U.S.

The judge postponed the effective date of his class-wide order for 14 days to give the Trump administration time to seek emergency relief from the federal appeals court in Washington. He also put off a decision on whether to certify a class of individuals who were subject to Mr. Trump’s new asylum rules and are no longer in the U.S.

“The significance of the decision cannot be overstated,” said Lee Gelernt, a lawyer with the American Civil Liberties Union, which is representing the plaintiffs. “The ruling not only means the U.S. will once again be a safe haven for those fleeing persecution but also reaffirms that the laws Congress enacts must be respected by the president.”

Since returning to the White House for a second term, Mr. Trump has rolled out a series of plans aimed at targeting migrants in the U.S. His efforts began on the first day of his second term, when Mr. Trump took unilateral action to prevent most migrants crossing the southern border from applying for asylum or withholding of removal, a type of relief that prevents the Department of Homeland Security from deporting a migrant to their home country because of likely persecution.

Mr. Trump’s proclamation cited an alleged “invasion” at the U.S.-Mexico border and directed administration officials to take action to “repel, repatriate, or remove any alien engaged in the invasion across the southern border of the United States.”

The migrants and immigrants’ rights groups sued the Trump administration in early February and sought to block enforcement of the president’s proclamation, arguing it is “as unlawful as it is unprecedented.”

Moss, appointed by former President Barack Obama, held a hearing in April to consider their bid to invalidate the plan.

In his decision, the judge found that neither the Constitution nor the Immigration and National Act authorize the changes in immigration law that Mr. Trump has sought to make. 

He wrote that the president “lacks the inherent constitutional authority” to supplant federal statutes governing removals.

“To hold otherwise would render much, if not most, of the INA simply optional,” Moss wrote.

As with his first term, immigration has remained a focal point of the president’s second term, and he has undertaken a number of actions that he says are aimed at targeting the purported “invasion” at the southern border. Many aspects of Mr. Trump’s immigration agenda have sparked legal battles. Mr. Trump has invoked a 1798 wartime law known as the Alien Enemies Act to deport Venezuelan migrants he claims are members of the gang Tren de Aragua and has ended programs put in place by former President Joe Biden that shielded nearly 1 million migrants from the threat of deportation.